SketchUp 2020: Finding and Using Your License Key and Authorization Number
While SketchUp 2020 could technically still validate older perpetual licenses (if users had active Maintenance and Support plans), the primary mechanism was the Subscription model. Sketchup 2020 License Key And Authorization Number
SketchUp 2020 was the last version to offer a perpetual license model before Trimble fully transitioned to a subscription-only model with SketchUp 2021 and beyond. If you purchased a perpetual license for SketchUp 2020 Pro at the time (before November 2020), you received a unique license key tied to your Trimble account. These keys are: SketchUp 2020: Finding and Using Your License Key
The Classic License allows installation on up to two devices (e.g., a desktop and a laptop), but only one can run the software at a time. If you purchased a perpetual license for SketchUp